Engineering of bone, cartilage, and osteochondral tissue offers promising alternative approaches for regenerative medicine as well as tools to study skeletal tissue developmental processes and disease models. To understand the electrotherapeutic factors and advance healing of musculoskeletal tissues, one needs to develop modalities for non-invasive, quantitative, multiscale imaging of the forming tissues. To date, there has not been a bioreactor system that allows real-time monitoring of clinically sized engineered tissues without sacrificing the samples or interfering with the cultivating condition, principally due to the size and portability of the culture system, and the fact that imaging systems are usually located in a separate facility. We propose to develop a new bioreactor system, which incorporates non-destructive imaging techniques to monitor bone, cartilage, and osteochondral tissue development in vitro. Our goal is to integrate separate efforts of two laboratories specializing in tissue engineering and radiological imaging toward the development of a portable, imaging- compatible bioreactor enabling quantitative on-line studies of complex cartilage/bone tissue constructs. We will rigorously test this hypothesis by studying bone formation by endochondral and intramembraneous ossification on a microscopic to macroscopic level. Three specific aims will be pursued: (a) Development of a portable bioreactor integrated with imaging, (b) CT bioreactor studies of cartilage/bone formation, and (c) -PIXE bioreactor studies of cartilage/bone formation. The anticipated scientific impact will be in significant new insights into bone formation through the development of non-invasive quantitative imaging at multiple scales.